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Causes and correlations in cambium phenology: towards an integrated framework of xylogenesis.

Rossi S, Morin H, Deslauriers A - J. Exp. Bot. (2011)

Bottom Line: The dependency links connecting the timing of xylem cell differentiation and cell production were defined and the resulting causal model was analysed with d-sep tests and generalized mixed models with repeated measurements, and tested with Fisher's C statistics to determine whether and how causality propagates through the measured variables.The higher correlations were observed between the dates of emergence of the first developing cells and between the ending of the differentiation phases, while the number of cells was significantly correlated with all phenological phases.Causal modelling suggested that the phenological phases involved in xylogenesis are closely interconnected by complex relationships of cause and effect, with the onset of cell differentiation being the main factor directly or indirectly triggering all successive phases of xylem maturation.

View Article: PubMed Central - PubMed

Affiliation: Département des Sciences Fondamentales, Université du Québec à Chicoutimi, Chicoutimi, Canada. sergio.rossi@uqac.ca

ABSTRACT
Although habitually considered as a whole, xylogenesis is a complex process of division and maturation of a pool of cells where the relationship between the phenological phases generating such a growth pattern remains essentially unknown. This study investigated the causal relationships in cambium phenology of black spruce [Picea mariana (Mill.) BSP] monitored for 8 years on four sites of the boreal forest of Quebec, Canada. The dependency links connecting the timing of xylem cell differentiation and cell production were defined and the resulting causal model was analysed with d-sep tests and generalized mixed models with repeated measurements, and tested with Fisher's C statistics to determine whether and how causality propagates through the measured variables. The higher correlations were observed between the dates of emergence of the first developing cells and between the ending of the differentiation phases, while the number of cells was significantly correlated with all phenological phases. The model with eight dependency links was statistically valid for explaining the causes and correlations between the dynamics of cambium phenology. Causal modelling suggested that the phenological phases involved in xylogenesis are closely interconnected by complex relationships of cause and effect, with the onset of cell differentiation being the main factor directly or indirectly triggering all successive phases of xylem maturation.

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Related in: MedlinePlus

Correlation matrix between the dates of cambium phenology (first enlarging, wall-thickening, and mature cell, ending of cell enlargement, and cell wall lignification) and the radial number of cells produced annually by black spruce during 2002–2009. One, two, and three asterisks correspond to a probability lower than 0.05, 0.01, and 0.001, respectively.
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fig3: Correlation matrix between the dates of cambium phenology (first enlarging, wall-thickening, and mature cell, ending of cell enlargement, and cell wall lignification) and the radial number of cells produced annually by black spruce during 2002–2009. One, two, and three asterisks correspond to a probability lower than 0.05, 0.01, and 0.001, respectively.

Mentions: Strong and significant correlations were observed between the dates of emergence of the first enlarging, wall-thickening, and mature cells, with Pearson correlations calculating positive coefficients r of between 0.64 and 0.74, and P <0.001 (Fig. 3). Accordingly, late onsets of cell enlargement led to delayed onsets of secondary cell wall formation and late emergences of mature cells in the xylem. In contrast, weak correlations were observed between the phases of onset and ending of differentiation, with r negative and lower than 0.24. The ending of cell enlargement was positively correlated with the ending of cell wall lignification, with r=0.50 and P < 0.001. The number of cells was significantly correlated with all phenological phases, with the greater coefficients resulting from the correlations with the endings of cell enlargement and cell wall lignification (r=0.51 and 0.54, respectively). Later dates of first observed enlarging, wall-thickening, and mature cells corresponded to lower cell productions, although the relationships appeared not to be perfectly linear at the higher numbers of cells. In contrast, greater numbers of cells were observed when cell enlargement and cell wall lignification occurred late in the season (Fig. 3).


Causes and correlations in cambium phenology: towards an integrated framework of xylogenesis.

Rossi S, Morin H, Deslauriers A - J. Exp. Bot. (2011)

Correlation matrix between the dates of cambium phenology (first enlarging, wall-thickening, and mature cell, ending of cell enlargement, and cell wall lignification) and the radial number of cells produced annually by black spruce during 2002–2009. One, two, and three asterisks correspond to a probability lower than 0.05, 0.01, and 0.001, respectively.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3295399&req=5

fig3: Correlation matrix between the dates of cambium phenology (first enlarging, wall-thickening, and mature cell, ending of cell enlargement, and cell wall lignification) and the radial number of cells produced annually by black spruce during 2002–2009. One, two, and three asterisks correspond to a probability lower than 0.05, 0.01, and 0.001, respectively.
Mentions: Strong and significant correlations were observed between the dates of emergence of the first enlarging, wall-thickening, and mature cells, with Pearson correlations calculating positive coefficients r of between 0.64 and 0.74, and P <0.001 (Fig. 3). Accordingly, late onsets of cell enlargement led to delayed onsets of secondary cell wall formation and late emergences of mature cells in the xylem. In contrast, weak correlations were observed between the phases of onset and ending of differentiation, with r negative and lower than 0.24. The ending of cell enlargement was positively correlated with the ending of cell wall lignification, with r=0.50 and P < 0.001. The number of cells was significantly correlated with all phenological phases, with the greater coefficients resulting from the correlations with the endings of cell enlargement and cell wall lignification (r=0.51 and 0.54, respectively). Later dates of first observed enlarging, wall-thickening, and mature cells corresponded to lower cell productions, although the relationships appeared not to be perfectly linear at the higher numbers of cells. In contrast, greater numbers of cells were observed when cell enlargement and cell wall lignification occurred late in the season (Fig. 3).

Bottom Line: The dependency links connecting the timing of xylem cell differentiation and cell production were defined and the resulting causal model was analysed with d-sep tests and generalized mixed models with repeated measurements, and tested with Fisher's C statistics to determine whether and how causality propagates through the measured variables.The higher correlations were observed between the dates of emergence of the first developing cells and between the ending of the differentiation phases, while the number of cells was significantly correlated with all phenological phases.Causal modelling suggested that the phenological phases involved in xylogenesis are closely interconnected by complex relationships of cause and effect, with the onset of cell differentiation being the main factor directly or indirectly triggering all successive phases of xylem maturation.

View Article: PubMed Central - PubMed

Affiliation: Département des Sciences Fondamentales, Université du Québec à Chicoutimi, Chicoutimi, Canada. sergio.rossi@uqac.ca

ABSTRACT
Although habitually considered as a whole, xylogenesis is a complex process of division and maturation of a pool of cells where the relationship between the phenological phases generating such a growth pattern remains essentially unknown. This study investigated the causal relationships in cambium phenology of black spruce [Picea mariana (Mill.) BSP] monitored for 8 years on four sites of the boreal forest of Quebec, Canada. The dependency links connecting the timing of xylem cell differentiation and cell production were defined and the resulting causal model was analysed with d-sep tests and generalized mixed models with repeated measurements, and tested with Fisher's C statistics to determine whether and how causality propagates through the measured variables. The higher correlations were observed between the dates of emergence of the first developing cells and between the ending of the differentiation phases, while the number of cells was significantly correlated with all phenological phases. The model with eight dependency links was statistically valid for explaining the causes and correlations between the dynamics of cambium phenology. Causal modelling suggested that the phenological phases involved in xylogenesis are closely interconnected by complex relationships of cause and effect, with the onset of cell differentiation being the main factor directly or indirectly triggering all successive phases of xylem maturation.

Show MeSH
Related in: MedlinePlus